초록 ▼

Proximity of a body, which may be a user's finger, to an electrode pair is sensed by a charge transfer capacitive measurement approach. The electrode pair thus acts as a key that can be arrayed with other electrode pairs to form a keypad, keyboard, linear slider control, or liquid level sensor. In o

Proximity of a body, which may be a user's finger, to an electrode pair is sensed by a charge transfer capacitive measurement approach. The electrode pair thus acts as a key that can be arrayed with other electrode pairs to form a keypad, keyboard, linear slider control, or liquid level sensor. In one embodiment of the invention each key is associated with an alternating voltage source and a pair of electrodes mounted on or within a solid dielectric substrate or panel so as to be separated from each other by a gap. The voltage source is connected to a driven electrode, a sampling charge detector is connected to a second, receiving, electrode, and the output of the charge detector is, in turn, fed into a signal processor. Disturbances in coupling between the two electrodes are detected through the solid substrate or panel material when a substance or object approaches or contacts the panel. The receiving electrode is a low-impedance node during the sampling phase of the process, which aids in keeping the sensor from being affected by wiring length or by extraneous objects near an output lead..

대표청구항 ▼

1. A method of operating a key by sensing the presence of a body proximate a coupling capacitor and spaced apart therefrom by a dielectric layer, the coupling capacitor comprising a driven plate and a receiving plate, the driven plate electrically connected to a signal generator supplying a pluralit

1. A method of operating a key by sensing the presence of a body proximate a coupling capacitor and spaced apart therefrom by a dielectric layer, the coupling capacitor comprising a driven plate and a receiving plate, the driven plate electrically connected to a signal generator supplying a plurality of voltage cycles, the receiving plate connected to a reference potential whenever it is not connected to processing circuitry comprising a charge integrator having two terminals, the method comprising the steps of:a) controlling one or more of a plurality of switching elements so as to set both terminals of the charge integrator to the reference potential; b) controlling one or more of the plurality of switching elements during a predetermined portion of each of a predetermined number of the voltage cycles, to connect the receiving plate to the charge integrator, thereby transferring electric charge from the receiving plate to the charge integrator; and; c) measuring a voltage on one of the two terminals of the charge integrator.